The present invention relates to a system for binding a boot to a ski, intended for the practice of cross-country skiing.
Ski boots presently worn for practising cross-country skiing are being more and more often designed with means for laterally guiding and retaining the heel so as to allow movement of the foot which remains as much as possible in the longitudinal axis of the ski, and thus enhance control of the ski itself.
Various types of construction for achieving such retention of the heel are known. For example, in one type of cross-country ski boot the sole cooperates with the ski via a cylindrical centering stud engaging in a corresponding hole in said sole. In this construction, the difficulty in exactly centering the foot on the ski is immediately apparent, as the hole in the sole must be engaged with the stud, said hole and said stud each being located in the zone of the heel. The difficulty of centering this type of boot on the ski is further increased in that snow may, at least partially, block up the hole in the sole, thus rendering this arrangement completely ineffectual.
similar difficulties in centering are encountered in other prior art constructions, where the foot is guided only when the heel of the boot comes to rest on the ski.
Thus, certain types of construction employ hard tips, disposed in triangles and projecting from the top surface of the ski, to penetrate in a zone of softer material, located beneath the heel, opposite said tips, when the foot reaches the final phase of its downward movement and comes to rest on the ski.
According to another embodiment, a flexible heel piece provided on each of its sides with a metal ridge cooperating with the heel of the boot to assure control thereof, is disposed on the ski.
In other known arrangements, notched sectors project from the top surface of the ski where they are fixed, to cooperate with the heel of the boot.
All of these prior art structures share the drawback that the centering of the boot on the ski is effected only in the final phase of the movement of the foot when said latter comes into contact with the ski. In fact, these means for controlling and guiding the boot assure centuring of said boot only in the last millimeters of the movement of the foot, and do not really prevent the off-centered and offset movements of the foot with respect to the axis of the ski which may occur during skiing on hilly terrain.
In such situations, the skier must then correct the positions of his foot during the striding motion, and this correction wastes time and even causes loss of balance, both of which is prejudicial to performances, particularly in competition.